Upright Perspective

by Arnold Schnitzer

Arnold Schnitzer

This Article Was Originally Published On: July 1st, 2014 #Issue 14.

In my shop I see many, many broken basses. A lot of the problems with these instruments could have been prevented by some simple maintenance – and by being aware of subtle and not-so-subtle changes in one’s bass. There are several things a bass owner can do to prolong the useful life of his/her instrument and to keep it sounding and playing its best. Here’s a partial list, along with suggestions on how to do your best as your instrument’s steward.


Early in the 20th century, King Tut’s tomb was opened after about 3,500 years. The wooden objects found in the tomb were in remarkable condition, and their glue joints were intact. That’s because the temperature and humidity in the underground vault never changed. I believe I read that the conditions in the tomb were about 60 degrees (Fahrenheit) and about 40% relative humidity. If a bass (or other stringed instrument) were kept in a non-variable climate like that, seams would never open, necks would not come loose, and weather-related cracks would be non-existent. Of course, basses are damaged by other things, such as string pressure and accidents, but for now let’s concentrate on the issue of humidity.

In a temperate, changeable climate, your instrument will go through noticeable changes in bridge height, neck angle and soundpost tension. It is impossible to prevent these changes, but by mitigating them, your bass will stay healthier and sound better. The biggest culprit is a rapid change of relative humidity, especially from dampness toward dryness. For example, transporting your bass from New Orleans (damp) to Phoenix (desert) will shock it and possibly cause some new open seams, cracks, and a tight soundpost, as well as dropping the string height. Going in the opposite direction will swell the bass, loosen the soundpost, and raise the string height. This is of course an extreme example, but spread out over months, this is what happens to your bass in many parts of the world that have distinct seasons. Exacerbating the situation is the fact that central heating systems, especially those that heat and circulate the air in a building, remove a lot of moisture as well. 

There are three tools every bassist should have to help prevent major damage in the dry months: 1) a good reliable humidifier; 2) a good reliable hygrometer (a gauge that measures relative humidity); 3) a well-padded and insulated cover, such as a Mooradian or Bobelock. Try to gradually wean your bass from high humidity to moderate as the winter or dry season approaches. In most areas, I recommend a relative humidity level in the 35 to 40% range during the dry times. Using a good padded bag during transport and storage helps, too. Sometimes, you must travel during dry times, or play in a venue with very low relative humidity. Fortunately, it usually takes a day or two for the wood of the bass to dehydrate, so as long as you have been keeping the instrument at 35 to 40%, it should be okay. Providing your bass’ top table was properly attached with weak hide glue, an occasional seam opening should be the worst damage that occurs. Keep in mind that the seams of a string instrument are its “safety valves;” breathe a sigh of relief when a seam opens, because this means you have avoided a crack.

For those times when you just can’t get your bass into a humidified environment, you can help a little by making a moisture diffuser. You’ll need two small zip-lock bags, a piece of string, two sponges, and a hole puncher. Punch a bunch of holes in the bags, then tie them together with a length of string. Wet the sponges, squeeze out excess water, place in the bags, zip them closed, and drop them in the f-holes of the bass. Adjust the string length so they hang freely. This will help a little, but will do nothing for humidifying the neck and fingerboard.

One last thing about winter (dry season) humidifying; don’t overdo it! If you keep your bass in a humid environment (say, 50-60%), then take it to a rehearsal or performance where the venue has forced air heating, the instrument will be shocked and will possibly suffer some damage.

Do plywood (laminated) basses need humidification? Yes, but it’s not as crucial, because the largest parts (the top and back plates) are not prone to cracking. However, older plywood basses were laminated with hide glue, and are susceptible to delamination when going through extreme weather changes and dryness, as well as extreme dampness, which can reactivate and loosen the glue which binds the layers together.

Bridge Position:

Three bad things occur when your bridge slips out of position: 1) your intonation will suffer; 2) the sound may change, and; 3) the bridge is prone to warping. In an extreme case, where the bridge feet have moved significantly in relation to the soundpost, your bass could suffer a bulge or crack in the top at the soundpost. In an extreme case, the bridge can topple; this usually makes the soundpost drop, as well.

It’s pretty simple to keep your bridge in the right place. Start by marking the feet of the bridge with a very soft pencil or china marker. Check the position of the feet often, making sure that they are straight in relation to each other, and centered between the f-holes on the bass’ top. If you need to move or rotate the feet, loosen the string tension somewhat and position them correctly. Write down the exact distance between the nut and bridge, measuring in the center of both, and check this length often. If you keep graphite in the bridge grooves, you will be able to easily adjust the position of the bridge top with a firm push or pull, using several fingers on the bridge. You can also make, or have made for you, a special indicator that fits between the end of the fingerboard and the bridge top to check the position.

Rosin on the Varnish:

When you play your bass with a bow, rosin sloughs off the hair and falls all over the bass, congregating mainly on the top, bridge, and in the c-bout ribs. Rosin is a sticky substance, and is made partially from tree-based materials similar to varnish components. If left on the instrument for a long time, the rosin actually digs into and degrades the varnish film. The result is an ugly mess of discoloration and roughness. When it settles on the bridge, it adds significant mass which can adversely affect the sound and response of your bass. It is best removed right after playing by wiping the instrument down with a soft cotton or micro-fiber cloth. If your bass has a significant rosin build-up, the task of removal and re-polishing should be given to a professional luthier, who may use both physical and chemical removal methods.

Nut and Bridge Grooves:

Whenever you change strings (which are best changed one at a time), it is a good idea to rub some graphite from a soft pencil into the bridge and nut grooves. This will help with accurate tuning and will also help to prevent strings unraveling or breaking at those important spots. If you change the type of strings you are using, pay attention to the relative diameters of the old vs. new ones. If you install strings that are thicker, the grooves may be too tight, and this can damage the strings and affect tuning. If you have a question whether your new strings will work okay in the existing grooves, and you don’t have sophisticated measuring equipment, lay each string in its groove, pull it tight with both hands, and work the string back and forth, feeling for a pinch. If the grooves need to be widened, special round-bottomed files should be used, and the grooves should angle slightly downward (toward the string ends) at both the bridge and nut, or a buzz may develop. When transitioning from thicker to thinner strings, you may need to have the nut and bridge adjusted to avoid sloppiness or buzzing in the grooves. Often times, it will work just fine.

In my next installment I will discuss strings, fingerboard, seams and cracks, edges and endpins. I’ll also take at crack at the dreaded emergency soundpost re-installation. Keep it Deep!